Hermetic refrigerant compressor



July 3, 1963 c. A. DUBBERLEY 3, 3,6

HERMETIC REFRIGERANT COMPRESSOR Filed July 7, 1955 FIGnZ I INVEN TOR.

CHARLES A. DUBBERLEY HIS ATTORNEY United States Patent 3,098,604HERMETIC REFREGERANT (XEMPRESSOR Charles A. Dubberiey, Mountain Lakes,N.J., assignor to General Electric (Jompany, a corporation of New YorkFiled .fuly 7, 1955, Ser. No. 520,554 7 Claims. (Cl. 230-296) Thepresent invention relates to hermetically sealed refrigerant compressorsand is more particularly concerned with an improved lubricatingarrangement for such compressors.

Hermetic refrigerant compressors comprise a motor compressor unitincluding a compressor for compressing the refrigerant and a motor fordriving the compressor sealed within a gas-tight casing. The lowerportion of the casing contains a body of lubricating oil which isemployed to lubricate the various bearing surfaces of the compressorunit. The remaining space with the hermetic casing is filled withrefrigerant vapor which may be at either low (suction) pressure or high(discharge) pressure depending upon the manner in which the hermeticcompressor is connected into the refrigerating system. In one form ofhermetic compressor of the type with which the present invention isconcerned the compressor and the motor for driving the compressor aremounted one above the other on a common vertical shaft. The shaft inturn is mounted in axially aligned bearings suitably supported by asupporting frame and to provide sufficient rigidity to the constructionat least one of these bearings is normally positioned adjacent the upperportion of the shaft above the normal oil level in the casing. In orderto provide the proper lubrication for any bearing surfaces above thenormal oil level, it is of course necessary to provide some means forconveying lubricating oil from the oil reservoir to such surfaces.

A proposed simple and low cost means for providing lubrication for theunimmersed bearing surfaces comprises a lubricant passage having aninlet end at the center of rotation of the lower or immersed end of thevertical shaft communicating with the body of lubricating oil and anoutlet port terminating on a circumferential surface of the shaftadjacent the bearing surface. During rotation of the shaft, centrifugalforces on the oil entering the inlet end of the passage causes the oilto flow upwardly through the passage to the surface to be lubricated.

While this proposed arrangement for lubricating unimmersed bearingsurfaces possesses a number of advantages including a freedom from anymoving parts other than those required for the motor compressor unit, inactual practice it has been found that the arrangement is not completelysatisfactory for use in connection with hermetic compressor employed tocompress a refrigerant .which is oil-soluble to any substantial extent.Examples of such refrigerants are the chlorinated fluorinatedhydrocarbon compounds such as those sold under the trade name Freon.With such oil soluble refrigerants and under certain conditions of use,the unimmersed bearing surfaces received inadequate lubricationresulting in bearing failure. It has now been discovered that thesebearing failures result primarily from the fact that the small quantityof refrigerant dissolved in the oil tends to separate or centrifugetherefrom in the lubricant passageway formed in the shaft so that thelighter free refrigerant vapor and foam formed as a result of theseparation prevents any substantial quantity of lubricant from reachingthe uppermost bearing surfaces.

It is an object of the present invention to provide an oil pumparrangement of the above described type including means for assuringpositive lubrication of unimmersed bearing surfaces.

Another object of the present invention is to provide a centrifugal oilpump for a hermetic refrigerant compressor comprising a lubricantpassage formed within the compressor shaft for centrifugally pumpinglubricating oil to unimmersed bearing surfaces and refrigerant ventingmeans in communication with the lubricant passage for venting from thepassage any refrigerant vapor and foam which would otherwise interferewith the supply of lubricating oil to unimmersed bearing surfaces.

Further objects of the invention will become apparent as the followingdescription proceeds and the features of novelty which characterize theinvention will be pointed out with particularity in the claims annexedto and forming a part of this specification.

In carrying out the objects of this invention, there is provided ahermetic compressor including a vertical shaft supported by bearingsurfaces at least one of which is arranged above the level of the oilreservoir contained in the hermetic casing. Means for supplying oil fromthe oil reservoir to the unimmersed bearing surfaces comprises alubricant passage having an inlet end at the lower or immersed end ofthe shaft and at approximately the center of rotation or axis thereofand one or more outlets on the circumferential surfaces of the shaft atunimmersed bearing surfaces or areas. In order to vent the refrigerantvapor and foam formed in the lubricant passage during rotation of theshaft and thereby provide for a continuous supply of refrigerant-freeoil to the unimmersed bearing surfaces, there is provided incommunication with the lubricant passage adjacent the upper end thereof,a refrigerant vent which extends from the lubricant passage through theaxis of rotation of the shaft and has its outlet on the opposite side ofthe shaft in communication with the interior of the hermetic casingabove the .body of lubricating oil.

For a better understanding of the invention, reference may be had to theaccompanying drawing in which the FIG. 1 is a side .elevational view,partially in section, of a hermetic refrigerant compressor incorporatingan embodiment of the invention; and

FIG. 2 is a partial sectional view illustrating another modification ofthe invention.

Referring to the drawing, there is shown a fhermetic compressorincluding a hermetic casing housing 1 in which is suitably supported arefrigerant compressor unit. ,The unit includes a frame 2 comprising twoaxially aligned bearings 3 and 4 in which is mounted a'verticallyextending shaft 5 having an eccentric portion 6 intermediate its upperand lower ends on which is mounted the connecting rod 7 of a compressor8 including piston 9. Means for driving the compressor comprises anelectric motor 11 positioned in the upper portion 12 ,of the hermeticcasing and having a rotor 13 'keyed'to the shaft 5. A thrust or coverplate 14 secured by :bolts 16 to the portion of the frame 2 overlyingthelower end of bearing 3 serves as a thrust bearing surface .for the shaftwithin the frame .2.

In order to provide a source of lubricating oil for the various bearingsurfaces 'of the-compressor unit there is employed a reservoir or bodyof oil 1. 8 in the lower por- .tion of the hermetic casing; This .bodyoflubricant is-of sufficient depth that the lower end of the shaftincluding at least a' portion of bearing 3 'is' substantially immersedin the reservoir and is lubricated :by the oil contained therein. Forthe purpose of providing lubrication for the upper main bearing 4 .andcrank .bearing o which in .the modification shown are disposed above the"body of oil and below the motor 11, .there is provided a centrifugalpumping arrangement includinga' lubricant -passage or duct in the shaft5 having its lower or inlet end at the center of rotation of the shaftbelow the oil level in the reservoir 18 and an upper outlet on theperipheral surface of the shaft encompassed by and in frictionalengagement with the upper bearing 4-. In the modification shown thislubricant passage comprises a horizontal, radially extending groove 20which with thrust plate 15 forms a radial passage and a vertical portionor passage 21 parallel to but offset from the vertical axis or center ofrotation 23 of the shaft. The lower end of the passage 21 communicateswith the radially extending groove 20 and the upper end terminateswithin or slightly above the portion of the shaft journalled in theupper unimmersed bearing 4. To assure lubrication of the lower bearingunder varying oil level conditions, this bearing can be force fed byextending groove 20 to the periphery of the shaft. Adjacent the upperend of the vertical passage 21 there is provided an oil port 19extending from the passage to the peripheral surface of the shaft withinthe bearing 4. By this arrangement oil entering the lower passage 20through the opening 22 in the thrust plate 15 is subjected tocentrifugal forces set up by rotation of the shaft and flows upwardlyalong the passageway 21 and outwardly through the oil port 19 tolubricate the bearing surfaces of the upper bearing 4. Intermediate theends of the shaft and in line with the connecting rod 7 there may alsobe provided one or more additional ports such as port 24 which isadapted to furnish lubricating oil to the bearing crank 6 formed betweenthe eccentric portions of the shaft and the connecting rod 7.

A compressor of this type is adapted to be connected into a refrigerantsystem to receive suction gas from an evaporator through the inletconduti 26 and to discharge compressed refrigerant through the outletconduit 27 to the condenser. The suction gas is introduced directly intothe interior of the hermetic casing and completely fills the spacewithin the casing while the compressed refrigerant from the compressor 8is discharged directly from the compressor through the outlet conduit27. As a result of this arrangement the refrigerant vapor drawn into thehermetic casing throughthe inlet 26 is always in contact with the bodyoil 18 provided in the lower part of the casing 1 and in the case ofoil-soluble refrigerants becomes absorbed or dissolved in that body ofoil. As a net result the oil eventually becomes saturated withrefrigerant vapor at the conditions of temperature and pressure existingwithin the hermetic casing 1. When this lubricating oil saturated withthe dissolved refrigerant is subjected to an increase in temperature, areduction of refrigerant vapor pressure, or to the centrifugal forcesset up in the horizontal portions of the oil passage formed within theshaft 5 and particularly in the radially extending passageway 20, thereis a reduction in pressure which causes some or all of the dissolved orabsorbed refrigerant to boil out and separate in either a vapor phase orin the form of an oil foam. This separation takes place not only in theradial passage 20 but also in the vertical passage 21. In this passage21, the refrigerant vapor tends to flow along the side of the passagenearest the center of rotation of the shaft while the oil, which is theheavier of the two, takes the opposite side. Also, since the refrigerantvapor is somewhat lighter than the oil it tends to collect along withthe refrigerant oil foam at the upper end of the passage 21 and depressthe static head of pure lubricating oil within the passage 21 to a pointwhere it is no longer able to effectively lubricate the upper bearingsurfaces forming part of the upper hearing 4.

In accordance with the present invention, this vapor or cfoam lockingtendency of the refrigerant liberated within the lubricant passage iseliminated by providing a refrigerant vent or passage 30 at the upperend of the vertical passage 21. In the modification shown in FIG. 1,this vent is a continuation of the oil port 19 and extends from theupper portion of the vertical passage 21 through the center of rotationor center line 23 of the shaft and terminates in an outlet end 33 on theopposite side of the shaft in direct communication with the upperrefrigerant vapor-filled portion of the hermetic casing.

The operation of the pump including the refrigerant vent 30 is quitesimple and effective. Upon rotation of the shaft 5, oil from thereservoir 18 enters through the opening or port 22 in the thrust plate14 which is submerged in the oil reservoir. Due to the centrifugal orradial forces to which the oil is subjected during its flow radiallyoutwardly through the passage 26, the oil is forced upwardly through thevertical passage 21. At the same time, refrigerant absorbed by the oilboils out and forms a separate phase or phases. As the centrifugalpressure forces both theoil and the refrigerant vapor or foam to travelup the vertical passage 21, the refrigerant tends to flow along the sidenearest the center of rotation or axis 23 of the shaft at a faster ratethan the heavier oil which follows a path along the outer side of thepassage 21. At the upper end of the passage 21, both the oil andrefrigerant vapor and foam reach the cross-port arrangement comprisingthe refrigerant vent 33 and the oil port 19. The heavier oil flowsoutwardly through port 19 away from the center of rotation of the shaftand into the main bearing oil groove 35. At the same time, the lighterrefrigerant is forced inwardly to the center of the shaft by thecontinuously rising column or head of oil and refrigerant in thevertical passage 21 and after passing the axis of the shaft is thrownoutwardly through the opposite end portion 33 of the refrigerant vent 30which opens into the upper refrigerant vapor-filled portion 12 of thehermetic casing above the bearing 4.

Preferably the radius from the center of rotation of the shaft 5 to theouter end of the refrigerant vent 30 is at least twice and preferablyabout 2.5 times as great as the radius to the near side of the verticalpassage 21. A difference of about this magnitude in the two radiiprovides a positive scavenging pump which effectively removes separatedrefrigerant from the oil pump and pas sages. On the other hand thestatic and centrifugal head of the oil in vertical passage 21 is suchthat it cannot be drawn inwardly across the center of rotation,consequently no oil spills out of the refrigerant vent 30.

While the oil port 19' and the refrigerant vent 30 are shown in FIGURE 1as having been formed by one drilling operation at such angle as toinclude an outlet for the oil port 19 into the upper main bearing 4 anda refrigerant vent outlet 33 above the bearing 4, any suitableconfiguration of these two ports or vents is equally effective as long:as the refrigerant vent 30 is level with or higher than the uppermostoil port 19 and so long as the refrigerant vent crosses the center ofrotation 23 of the shaft.

In FIG. 2 there is shown a modification of the present invention whichincludes both means for venting refrigerant from the vertical oilpassage and also for ventilating the groove within the upper bearing 4.In this modification, oil vents are provided for both the upper andlower portions, that is the upper portion 36 and the lower portion 37which are separated by the groove 35. The upper portion 36 is lubricatedby the oil vent 39 and the lower portion by the oil vent 40 whilerefrigerant is removed from the top of the vertical passage 21 through ahorizontally extending refrigerant vent 41. To relieve my refrigerantvapor pressure which may be set up: within the groove 35, there isprovided an additional vent 42 connecting this groove with the verticalpassage 21. This additional passage 42 is parallel to vent 40 andextends from passage 21 through the axis of the shaft to the groove 35.

The motor compressor unit may be of any type that includes a verticaldrive shaft one end of which is immersed in an oil reservoir and theother end of which extends vertically upwardly and is supported in suchposition by one or more unimmersed bearing surfaces. For example, arotary compressor or scotch-yoke type of compressor can be substitutedfor the one illustrated, the only requirement being that the shaft besuch that there can be drilled or otherwise formed in the shaft alubricant passage extending approximately from the lower end of theshaft at center of rotation thereof upwardly to the unimmersed bearingsurfaces and that this passageway have a radial component such that theoil entering the lubricating passage will be subjected to a centrifugalforce or pumping action sufiicient to provide an oil head sufficient toreach all of the unimmersed surfaces requiring lubrication.

By the present invention there has been provided a low cost lubricatingarrangement which provides positive lubrication of the unimmersedbearing surfaces with substantially refrigerant-free oil. Thelubricating arrangement builds up an oil pressure or head very rapidlywhen the compressor is first started with resultant low starting wear.It also maintains a constant oil pressure at all bearing surfaces underall conditions of temperatures, pressures and foaming existing withinthe oil reservoir. Unlike many lubricating systems for hermeticcompressors, the system of the present invention requires no flow orby-passing of oil through the hearings to flush refrigerant from the oilpassages and bearing surfaces and with the resultant lower over-allpumping rates for the oil, there is less agitation of the oil in the oilreservoir so that any dirt which may be present in this oil can settleto the bottom of the reservoir where it will remain indefinitely. Inaddition, the quantity of oil pumped by the lubricating system of thepresent invention is limited to that amount actually required to make upthe leakage from the bearings and this is held to a minimum since thebearings require no venting of refrigerant directly to the casing.

While there has been shown and described specific embodiments of thisinvention 'it is to be understood that the invention is not limited tothe particular forms shown and described and it is intended by theappended claims to cover all modifications within the spirit and scopeof the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a refrigerating compressor, the combination of a housing havingtherein a refrigerant space and a lubricant storage space; a shaftrotatably mounted within said housing and having therein a lubricantreceiving passage communicating with said lubricant space and aconnecting inclined vent passage communicating with said refrigerantspace, the inclination of said vent passage being in a direction towardthe center line of said shaft to thereby prevent the passage oflubricant through said vent passage.

2. In a refrigerant compressor of the type including avertically-disposed rotary drive shaft and a bearing surface engaging anupper portion of said shaft, the lower end of the shaft being formedwith a horizontal duct extending from the axis of the shaft and with avertical duct intercepting the horizontal duct at a point remote fromthe axis, said upper portion of said shaft being formed with a lateralduct extending from said vertical duct to a point on the periphery ofsaid shaft engaged by said bearing surface, and means forming an oilreservoir around the lower end of the shaft communicating with saidhorizontal duct therein and extending upwardly above the horizontal ducttherein to a level below said lateral duct, whereby upon rotation of theshaft oil may be forced centrifugally through said horizontal duct andupwardly to said lateral duct, that improvement which comprises a ventprovided in said shaft extending from said lateral duct to the peripheryof the shaft at an uncovered portion thereof above said lateral duct,whereby refrigerant vapor in said vertical and lateral ducts may escapefreely therefrom, said vent being disposed between the lateral duct andshaft periphery to pass through the axis of rotation of the shaft,thereby to establish a centrifugal force when the shaft is rotatedopposing the flow of oil therethrough.

3. In a refrigerant compressor of the type having a cylinder and apiston reciprocably mounted in the cylinder, a

drive shaft angularly disposed to the cylinder and having upper andlower concentric portions and an intermediate eccentric portion alignedwith the piston, a connecting rod between the piston and eccentricportion and a wrist pin between the piston and adjacent end of theconnecting rod, the lower end of the shaft being formed with ahorizontal duct extending from the axis of the shaft and with a verticalduct intercepting the horizontal duct at a point remote from the axis,said eccentric portion being formed with a lateral duct extending fromsaid vertical duct to the periphery of the eccentric portion, and meansforming an oil reservoir around the lower end of the shaft communicatingwith said horizontal duct therein and extending upwardly above thehorizontal duct therein to a level below said lateral duct, whereby uponrotation of the shaft oil may be forced centrifugally through saidhorizontal duct and upwardly to the eccentric portion, that improvementwhich comprises forming the eccentric portion with a vent extending fromsaid lateral duct to the periphery of the shaft at an uncovered portionthereof above the connecting rod, whereby refrigerant vapor in saidvertical and lateral ducts may escape freely therefrom and disposingsaid vent between the lateral duct and shaft periphery to pass throughthe axis of rotation of the shaft, thereby to establish a centrifugalforce when the shaft is rotated, opposing the flow of oil there'through.

4. A hermetic refrigerant compressor comprising a hermetic casingincluding a lower portion containing a body of lubricating oil and anupper portion containing refrigerant vapor, a refrigerant compressorunit positioned within said casing and including a vertically-disposedshaft having its lower end submerged in said body of lubricating oil, abearing supporting said shaft and positioned in the upper portion ofsaid casing above said body of oil, said bearing including upper andlower portions and a groove therebetween, and means for lubricating saidbearing comprising a radially extending passageway in the submergedlower portion of said shaft having its inner end in open communicationwith said body of oil, a vertical passage in said shaft parallel to andoffset from the center line of said shaft and extending from saidradially extending passage upwardly to a point within said shaft abovethe upper portion of said bearing, oil outlet ports in said shaftextending from the upper portion of said vertical passage to thesurfaces of said shaft encompassed by the upper and lower portions ofsaid bearing in a direction away from the axis of said shaft, ahorizontal refrigerant vent in said shaft having an inlet endcommunicating with said vertical passage at a point at least as high asthe uppermost of said oil outlet ports, said vent passing through theaxis of said shaft and terminating on the opposite side of said shaft ata point exposed to the refrigerant Vapor in the upper portion of saidcasing, and an additional passage in said shaft parallel to saidrefrigerant vent, said additional passage extending from said verticalpassage through the axis of said shaft and opening into said groove onthe opposite side of said shaft.

5. In a refrigerating compressor, the combination of a housing havingtherein a refrigerant space and a lubricant storage space, a shaftrotatably mounted within said housing, and a bearing surface engagingsaid shaft above said lubricant space, said shaft having therein avertical lubricant receiving passage having an inlet communicating withsaid lubricant space and an outlet communicating with said bearingsurface, that improvement which comprises a refrigerant vapor vent insaid shaft having an inlet end communicating with said vertical passageat a point at least as high as said outlet and its outlet endcommunicating with the refrigerant space in the upper portion of saidcasing whereby refrigerant vapor in said vertical passage may escapefreely from said vertical passage, said vent passing through the axis ofsaid shaft thereby establishing a centrifugal force in said vapor ventwhen the shaft is retated opposing the flow of oil therethrough.

6. In a hermetic refrigerant compressor comprising a hermetic casingincluding a lower portion containing a body of lubricating oil and anupper portion containing refrigerant vapor, a refrigerant compressorunit positioned within said casing and including a vertically-disposedrotary drive shaft having its lower end submerged in said body oflubricating oil, a bearing surface supporting said shaft and positionedin said casing above said body of oil, and means for lubricating saidbearing surface comprising a radially extending passageway in thesubmerged lower portion of said shaft having its inner end in opencornmunication with said body of oil, a vertical passage in said shaftparallel to and offset from the center line of said shaft and extendingfrom said radially extending passage upwardly to a point within saidshaft adjacent said bearing surface, an oil outlet port in said shaftextending from the upper portion of said vertical passage to the surfaceof said shaft encompassed by said bearing surface in a direction awayfrom the axis vof said shaft, that improvement which comprises arefrigerant vapor vent in said shaft having an inlet end communicatingwith said vertical passage at a point at least as high as said oiloutlet port and its outlet end communicating with the refrigerant vaporin the upper portion of said casing whereby refrigerant vapor in saidvertical passage and port may escape freely therefrom, said vent passingthrough the axis of said shaft thereby establishing a centrifugal forcein said vapor vent when the shaft is rotated opposing the flow of oiltherethrough.

7. In a hermetic refrigerant compressor of the type including a hermeticcasing and a compressor unit in said casing comprising avertically-disposed rotary drive shaft and a bearing surface engaging anupper portion of said shaft, the lower end of the shaft being formedwith a horizontal duct extending from the axis of the shaft and with avertical duct intercepting the horizontal duct at a point remote fromsaid shaft axis, said upper portion of said shaft being formed with alateral duct extending from said vertical duct to a point on theperiphery of said shaft engaged by said bearing surface, and meansforming an oil reservoir in said casing around the lower end of theshaft communicating with said horizontal duct therein and extendingupwardly above the horizontal duct to a level below said lateral ductwhereby upon rotation of the shaft oil may be forced centrifugallythrough said horizontal duct and upwardly through said vertical duct tosaid lateral duct, that improvement which comprises a vent provided insaid shaft extending from said vertical duct at a point at least as highas said lateral duct to the periphery of the shaft at a portion thereofcommunicating with said casing above said oil reservoir, wherebyrefrigerant vapor in said vertical and lateral ducts may escape freelytherefrom, said vent being disposed between the vertical duct and shaftperiphery to pass through the axis of rotation of the shaft, thereby toestablish a centrifugal force when the shaft is rotated opposing theflow of oil thereth-rough.

References Cited in the file of this patent UNITED STATES PATENTS2,164,405 Hintze July 4, 1939 2,274,942 Touborg Mar. 3, 1942 2,312,596Smith Mar. 2, 1943 2,423,719 M'ufily July 8, 1947 2,500,751 Halfv-arsonMar. 14, 1950

1. IN A REFRIGERATING COMPRESSOR, THE COMBINATION OF A HOUSING HAVINGTHEREIN A REFRIGERANT SPACE AND A LUBRICANT STORAGE SPACE; A SHAFTROTATABLY MOUNTED WITHIN SAID HOUSING AND HAVING THEREIN A LUBRICANTRECEIVING PASSAGE COMMUNICATING WITH SAID LUBRICANT SPACE AND ACONNECTING INCLINED VENT PASSAGE COMMUNICATING WITH SAID REFIGERANTSPACE, THE INCLINATION OF SAID VENT PASSAGE BEING IN A DIRECTION TOWARDTHE CENTR LINE OF SAID SHAFT TO THEREBY PREVENT THE PASSAGE OF LUBRICANTTHROUGH SAID VENT PASSAGE.